This invention relates to a shock absorber made of laminated paper, which is easy for recycling or disposal. The shock absorber is in the form of a flat bag that can be inflated with air to perform shock absorbing functions due to a spring-like effect of the packed air during use. This invention is also related to a package with such shock absorbers.
When a product is shipped, it is usually packed in a corrugated fiberboard carton in which shock absorbers are packed in gaps between the product and the carton to stabilize the product in the package and to protect the product from an externally applied shock.
Shock absorbers for use in packaging include granulated shock absorbers that are put in containers in bulk or in bags, and sheet-shaped shock absorbers for wrapping a product. These are called fill-type shock absorbers. There is another type of shock absorbers called cushioning molds that are molded to mate the shapes of the products.
From the viewpoint of materials, shock absorbers are classified into plastic-based elements, paper-based elements, starch-based elements, and others. Plastic-based elements include granulated and sheet-like shock absorbers made of polystyrene foam (EPS), polyethylene foam (EPE), polypropylene foam (EPP), ethylene-styrene copolymer, polyurethane foam (PU), and so forth. Paper-based elements include those made of corrugated fiberboard, molded pulp, triplicate kraft paper, and paper tubes. Starch-based elements include granulated shock absorbers of hybrid cornstarch, etc.
Shock absorbers and packages have disposable forms for easier distribution, and are disposed of after their roles in shipping and protection of products. However, shock absorbers are more bulky than packages and cause serious problems in various respects, such as storage, depository and disposal.
Among various shock absorbers, paper-based and starch based shock absorbers are inferior to plastic-based shock absorbers in terms of resistance to water, resistance to pressure and resistance to shocks; however, the calorific value is low when they burn, and they can be recovered and recycled as ordinary waste. In particular, they are biodegradable and easily disposable.
In contrast, although plastic-based shock absorbers are superior in cushioning performance and stability, the calorific value is high when they burn, and they cannot be burned in incinerators. Moreover, when they are disposed as industrial waste, the possibility of recycling them is low.
Under the circumstances, air-bag-type shock absorbers have been developed to overcome the problems of storage and depository. These air-bag-type shock absorbers are made of a sheet material in form of bags that can be made small before and after use as shock absorbers, but that can be inflated like balloons by filling them with air or gas when they are used to absorb external vibrations or impulses. The sheet material forming the air-bag-type shock absorbers must have a high gas impermeability to reliably confine air or gas. For this purpose, they are made by stacking polyethylene, nylon or other plastic films, or by stacking a polyethylene or other plastic film on a paper sheet material such as kraft paper.
The plastic-based materials generate a high heat, and/or produce toxic gases when they burn. Therefore, incineration by incinerators is not acceptable for their disposal, and they must be disposed of as industrial waste by land reclamation or earth filling.
Moreover, since these elements do not decompose under natural environmental conditions, they are felt to cause problems regarding earth filling facilities and environmental pollution, and severe regulations are being made about their disposal.
Moreover, since polyethylene is stacked or bonded to paper material, it is difficult to separate the paper material from the laminated plastic films, and a special system is required for retrieving and reclaiming the paper material alone. As a result, also because a retrieving or recovering system has not been established, these air-bag-type shock absorbers are currently discarded or burned in the form of laminated paper. Therefore, even with the air-bag-type shock absorbers, environmental problems still remain.
Under the circumstances, it is important to select materials that can be stored compactly before their actual use and that can be recycled or separated without producing toxic by-products so as to reduce the volume of the shock absorbers after use and to overcome waste disposal problems.
It is further required to prevent a shock absorber from yielding to static force and to develop a package that does not transmit a dynamic force caused by a drop, etc. to the carton content and a shock absorber that can absorb a dynamic force.
For example, Japanese Patent Laid-Open No. 7-189182 (1995) discloses laminated paper for a shock absorber, and Japanese Patent Laid-Open 7-165266 (1995) discloses a method for fabricating a shock absorber.